Daniel J Hannon

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Translation of an observer through a static environment generates a pattern of optical flow that specifies the direction of self-motion, but the retinal flow pattern is confounded by pursuit eye movements. How does the visual system decompose the translational and rotational components of flow to determine heading? It is shown that observers can perceive(More)
Rod sensitivity was measured with a criterion-free psychophysical method at 10 deg in the horizontal meridian of the nasal field of the left eye on 26 young (mean age, 24.1 yr) and 14 older (mean age 72.6 yr) observers in good ocular health. A 1 deg, 90 msec stimulus was delivered by means of a free-viewing optical system under computer control. Stimulus(More)
The relationship between videotape ratings of pain behavior and the flexion-relaxation phenomenon was evaluated in a sample of 39 chronic low-back pain patients. The results showed that guarded movement explained approximately 27% of the variability in the flexion-relaxation phenomenon, adjusting for pain intensity rating. There were no significant(More)
OBJECTIVE To develop a prototype electronic ruler for assessment of fetal heart rate (FHR) variability on an electronic monitor and test its reliability and accuracy. STUDY DESIGN A prototype electronic ruler was designed and developed for assessment of FHR variability on electronic monitors. The electronic ruler consisted of horizontal bands that were(More)
Risk is a function of the probability of an event and the severity of the consequences of that event. Any discussion of issues of risk in surface operations must include a valid and reliable measure of the severity of the outcome of runway incursions. This paper describes an automated method for rating the severity of the outcome of runway incursions. This(More)
Inquiry-based methods are effective for STEM education, but they are perceived as difficult to implement. Often teachers have not experienced inquiry-based learning themselves, which limits their appreciation of their value of these methods. Changing this requires modifications at the classroom level to simplify implementation of inquiry-based methods and(More)
For decades, the social sciences have provided the foundation for the study of humans interacting with systems; however, sparse, qualitative, and often subjective observations can be insufficient in capturing the complex dynamics of modern sociotechnical enterprises. Technical advances in quantitative system-level and physiological instrumentation have made(More)
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